Published online by Cambridge University Press: 12 June 2017
Field studies were conducted near Beechwood, WI in 1986 and Sturgeon Bay, WI in 1987 and 1988 to evaluate herbicide treatments for control of triazine-resistant common lambsquarters (TR-CHEAL) in corn. AH PRE and many early postemergence (EP) and POST treatments were less effective in 1988 than in 1986 or 1987 due to drought. Atrazine, cyanazine, and metolachlor PRE controlled less than 15% TR-CHEAL late-season over the three years. Dicamba or pendimethalin applied PRE controlled 88 to 99% late-season TR-CHEAL in 1986 and 1987. Late-season TR-CHEAL control in 1986 and 1987 from acetochlor plus atrazine, alachlor plus atrazine, and metolachlor plus linuron applied PRE ranged from 58 to 86%. Pendimethalin plus cyanazine or atrazine applied EP controlled TR-CHEAL 97% or more late-season in 1986 and 1987, while pendimethalin plus dicamba plus atrazine applied EP controlled TR-CHEAL 97% or more each year. Late-season TR-CHEAL control from tridiphane plus cyanazine or atrazine EP was less than 58%. Late-season TR-CHEAL control from dicamba, 2,4-D amine, pyridate, and thifensulfuron applied POST was 87 to 99% each year, and was 94 to 99% in 1986 and 1987 from bromoxynil or bentazon applied POST. Dicamba, thifensulfuron, pendimethalin, pyridate, and 2,4-D amine were most effective in controlling TR-CHEAL in corn.